Question: When evaluating whether an ambiguous, or possibly misleading statement is geneivat da'at does the Torah use reasonable-man standard or ignorant-man standard?
Rabbi Levine posits that the Torah uses reasonable man standard. He derives this from a number of sources.
A case in messechet Hullin 94a:
Mar Zutra was traveling from Sikara to Mahoza while Rava and Rav Safra were going to Sikara. They passed each other on the way and Mar Zutra thanked the Rabbis for coming out to greet him. He assumed that the purpose of their trip was soley to show him honor.
Rav Safra said, "We had no idea you were coming."
Rava said to Rav Safra, "You did not have to tell him that."
Rav Safra said back, "but then we would be deceiving him."
To which Rava replied, "No we would not. He would be deceiving himself."
Rabbi Levine posits that since it was unreasonable for Mar Zutra to expect that the others came all taht way to meet him they had no responsibility to correct him. If theoretically it would have been reasonable that the Rabbis had come then they would have to correct him.